Conventional liquid crystal displays include transmissive type liquid crystal displays and reflective liquid crystal displays. Besides them, transflective type liquid crystal displays are proposed, which use ambient light, like reflective liquid crystal displays, in light places, and use an internal light source such as a backlight to make display visible, in dark places (see Patent Literatures 1 and 2 below). Such transflective type liquid crystal displays use both reflective and transmissive display systems and select either of reflective display mode and transmissive display mode depending on ambient brightness, so that they can provide clear display even in dark environments while reducing power consumption. Thus, they are suitable for display parts of mobile devices.
Concerning such transflective type liquid crystal displays, a certain liquid crystal display is proposed, which includes a liquid crystal layer sandwiched between upper and lower substrates and includes a reflective film that is a metal film, such as an aluminum film, having apertures for light transmission and formed on the inside surface of the lower substrate, wherein the reflective film functions as a transflective plate. When this system operates in a reflective mode, ambient light incident from the upper substrate side is allowed to pass through the liquid crystal layer and then reflected from the reflective film on the inside surface of the lower substrate and allowed to pass through the liquid crystal layer again and emitted from the upper substrate side to contribute to display. In a transmissive mode, light incident from a backlight on the lower substrate side is allowed to pass through the liquid crystal layer from the apertures of the reflective film and then emitted from the upper substrate side to the outside to contribute to display. In the region having the reflective film, the aperture region serves as a transmissive display region, while the remaining region serves as a reflective display region.
In liquid crystal displays, polarizing plates are used, and in order to improve image quality, optical films made of various polymer materials are used as optical compensation layers. Optical compensation layers are properly selected depending on the liquid crystal display mode (such as twisted nematic (TN), vertical alignment (VA), optically compensated bend (OCB), and in-plane switching (IPS)). For example, conventional reflective or transflective VA mode liquid crystal displays have the problem of contrast reduction, because they can cause light leakage when black viewing is displayed. In VA mode liquid crystal cells, therefore, circularly polarizing plates with a quarter wavelength plate are used as optical compensation layers in order to widen the viewing angle of the liquid crystal displays. For example, uniaxially oriented polymer films are used for such optical compensation layers.
An optical compensation layer-attached polarizing plate with a large overall thickness is undesirable for liquid crystal displays, which should be designed to be thin. Liquid crystal displays can be placed in various environments of severe temperature or the like, and particularly under heated conditions, unevenness or irregularities can easily occur due to film shrinkage and the like. Thus, it is desired that uneven heat-up should be prevented in optical compensation layer-attached polarizing plates.
Patent Literature 1: JP-A No. 11-242226
Patent Literature 2: JP-A No. 2001-209065